Along with the increase of amount of data handled by the storage apparatus, it is even more required to, for example, utilize storage resources efficiently, construct an efficient platform for achieving operation at a minimum cost, and achieve flexible operation status permitting detailed support to the user. To satisfy these requirements, the provision of storage areas based on storage pools, the dynamic migration of storage resources by hierarchization, and others are being performed in units of small storage areas such as pages.
As for dynamic migration, for example, Patent Literature (PTL) 1 discloses, monitoring access frequencies of physical data, moving physical data of high access frequency to high-speed disk drives, moving physical data of low access frequency to low-speed disk drives.
PTL 2 discloses, as for migration performed in accordance with usage frequencies and the like of volumes, in order to permit appropriate monitoring of the performance of the target volume and re-migrating the data in a short time, copying all the data from the source volume to the target volume, switching the access path of the host to the target volume after copying, maintaining pair of copies between the volumes even after copying, managing the difference generated between the source volume and the target volume, monitoring the performance of the target volume with reference to the index in accordance with the type of the target volume, determining whether or not the status before data migration is to be restored in accordance with the monitoring result, and, if the status is to be restored, copying the differential data from the target volume to the source volume and switching the access path of the host to the source volume.
PTL 3 discloses, in the case of performing migration from a storage apparatus of high performance to a storage apparatus of low performance due to reduction of access frequency, when cancellation of migration is made for a reason that the processing performance is far lower than expected or other reasons, in order to solve problems such as the migration cannot be cancelled after the completion confirmation operation, or migration with the source and the target replaced needs to be performed again, and the like, based on the completion date and time of the performed migration and the update date and time of the volumes, determination is made on whether or not the selected source volume and the target volume were updated after completion of the performed migration, and, if both the selected source volume and the target volume are determined to have not been updated, cancellation of the migration performed is made by setting the storage subsystem so that the host computer accesses the source volume.